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View Full Version : cut this for boost guage?



unknownvirus
07-09-2004, 11:30 AM
http://mywebpages.comcast.net/khizar/guageline.jpg
not my car :-)

Zodiak
07-09-2004, 11:31 AM
nope, same spot, but on the other side of the manifold (towards the back of the engine). It's a lot closer so can run less hose.

Zodiak
07-09-2004, 11:36 AM
Ah found a picture. tap into the vac line back there
http://www.fastaudi.net/a4/library/full/engine.jpg

Burntaudi
07-09-2004, 11:43 AM
Originally posted by Zodiak
nope, same spot, but on the other side of the manifold (towards the back of the engine). It's a lot closer so can run less hose.

I disagree I think the one circled in the picture is the better option.

For a couple of reasons:

If you get a leak tying into the FPR line it will cause the car to burn lean.

If you use the one at the front it will be able to tell if your BPV is going bad.

unknownvirus
07-09-2004, 11:43 AM
ahhh u guys rock

unknownvirus
07-09-2004, 11:44 AM
well sorta
now im torn

DDQ
07-09-2004, 11:45 AM
I would NOT cut the FPR line, as Burntaudi explained.

Just tap the one in you first pic, in the front of the engine bay, and you'll have no worries.

Burntaudi
07-09-2004, 11:47 AM
Originally posted by unknownvirus
well sorta
now im torn

well either one will work...I personally like it hooked up at the BPV hose. I've had it hooked up there for a couple of years with no trouble.

Zodiak
07-09-2004, 11:49 AM
You can go with either, I chose the one in the back because I didn't want to run a lot of extra hose through the engine bay and the hose running to the bpv is the one that breaks the most (for me atleast).

The line to the FPR is so short that if you get a leak back there, it is very easy to source and replace (don't have to get under the car). Once you've dealt with a failing BPV once, you'll know the symptoms (not holding boost and the howling sound you get when it sticks open).

But they are both equally easy to tap into so just pick one. Each has its own benefit in my eyes.

JMG
07-09-2004, 11:55 AM
I wouldnt cut the fuel pressure line. There is no need to use that one, and is more of a PITA if there is a leak.

Instead, go by the APR write-up. It shows you exactly which hose to slice into.

http://www.goapr.com/Audi/support/boost_gauge_pod.pdf

Hose isn't so expensive as to change tapping locations for length.

unknownvirus
07-09-2004, 11:56 AM
haha i just dont want problems
i have 84 k miles
i dont need probs!
ill cut the one in the front
and ill come after all of u..if something leaks

Devious27t
07-09-2004, 11:58 AM
that is an unfounded notion and i would say its false.... the fuel pressure line is actually a more accurate reading of boost pressure and i can tell you from experience that a leak in that hose does not make you run lean.... i have had two incidents with it and neither time have i run lean from it. if you know what surge feels like its not hard to tell when your BPV is going bad. or just say no to 710N

Originally posted by Burntaudi
I disagree I think the one circled in the picture is the better option.

For a couple of reasons:

If you get a leak tying into the FPR line it will cause the car to burn lean.

If you use the one at the front it will be able to tell if your BPV is going bad.

JMG
07-09-2004, 12:06 PM
Here, I took a quick pic... Follow the blue hose.

http://home.comcast.net/~jmg703/pics/gauge_vactap_006.jpg

JMG
07-09-2004, 12:12 PM
Originally posted by DVS18t
that is an unfounded notion and i would say its false.... the fuel pressure line is actually a more accurate reading of boost pressure and i can tell you from experience that a leak in that hose does not make you run lean.... i have had two incidents with it and neither time have i run lean from it. if you know what surge feels like its not hard to tell when your BPV is going bad. or just say no to 710N

Did you get VAG readings to make sure you weren't running lean? Logically, a leak on that line will lower fuel pressure. Wouldn't that mean you run lean during boost?

This has been debated hundreds of times at AW, and there is no need to run extra risk of running lean. Why bother? Just tap the vac to the manifold. Readings are still accurate. Variance is little to none for the purposes of a gauge.

Zodiak
07-09-2004, 12:33 PM
I'm pretty sure AWE taps into the intake mani to FPR line for their gauge install. And even if you get a vac leak, it would take all of 2 seconds to pop the hood and check that 4" or vac line to see if the leak is coming from there and another minute to replace it. And I'm still unsure if the lean condition is as deadly as many make it out to be. A small vac leak there will quickly show on the boost gauge and driving with a tiny leak like that isn't going to do any noticable damage in the few miles it takes you to get to a hard wear store or temporarily patch up the leak.

JMG
07-09-2004, 01:01 PM
Originally posted by Zodiak
I'm pretty sure AWE taps into the intake mani to FPR line for their gauge install. And even if you get a vac leak, it would take all of 2 seconds to pop the hood and check that 4" or vac line to see if the leak is coming from there and another minute to replace it. And I'm still unsure if the lean condition is as deadly as many make it out to be. A small vac leak there will quickly show on the boost gauge and driving with a tiny leak like that isn't going to do any noticable damage in the few miles it takes you to get to a hard wear store or temporarily patch up the leak.

Once again.. why bother risking it? APR and most of the tuning community tap the other line.

agravic 2.0
07-09-2004, 01:08 PM
both locations are indeed "intake manifold" pressure. and either will work fine (given no leaks)
i chose the back because it is a more accurate reading as the line terminates at the FPR, the one in the front has more volumetric changes to the bpv.

just make damn sure all connections are secure if you use the one in the back. since i replaced it with a upgraded internally braided line, its not going to crack and potentially leak like the stock hose.

JMG
07-09-2004, 01:21 PM
Originally posted by agravic 2.0
both locations are indeed "intake manifold" pressure. and either will work fine (given no leaks)
i chose the back because it is a more accurate reading as the line terminates at the FPR, the one in the front has more volumetric changes to the bpv.

just make damn sure all connections are secure if you use the one in the back. since i replaced it with a upgraded internally braided line, its not going to crack and potentially leak like the stock hose.

clear out your PMs bro! I cant respond to your PM.

agravic 2.0
07-09-2004, 01:37 PM
oops. sorry!! ;)

Devious27t
07-09-2004, 01:56 PM
Originally posted by JMG
Did you get VAG readings to make sure you weren't running lean? Logically, a leak on that line will lower fuel pressure. Wouldn't that mean you run lean during boost?

This has been debated hundreds of times at AW, and there is no need to run extra risk of running lean. Why bother? Just tap the vac to the manifold. Readings are still accurate. Variance is little to none for the purposes of a gauge.

that would be the case if boost werent a derivation of MAP pressure, if there is a vacuum leak manifold pressure will be reduced and thus boost will be retarded.... iirc i was actually running a little bit rich and yes i was taking vag readings.... boost was retarded to about 4psi i believe.

Devious27t
07-09-2004, 01:58 PM
Originally posted by JMG
Once again.. why bother risking it? APR and most of the tuning community tap the other line.

i have personally never had any friends do that and audis are the only cars that i have seen any one tap a line other then the FPR if you look at any boost gauge install instruction guide they specifically say to tap the FPR line. why would they do that if it was so dangerous.

unknownvirus
07-09-2004, 02:34 PM
ok all done..installed on the non fpr line
what is the stock boost i should look for
its not really spiking
but it builds and holds at like 6-7
and if i let go of the gas..it drops to like 20 vac
thanx u guys

Burntaudi
07-09-2004, 02:37 PM
Originally posted by unknownvirus
ok all done..installed on the non fpr line
what is the stock boost i should look for
its not really spiking
but it builds and holds at like 6-7
and if i let go of the gas..it drops to like 20 vac
thanx u guys

Are you stock? sounds about right.

unknownvirus
07-09-2004, 02:42 PM
ya im stock
its a 97..and i hear it doesnt make as much as newer models
cant realyl get it past 7 psi
but just checking guys
thanx